Resin hose connecting structure

ABSTRACT

A resin hose connecting structure includes a resin hose including a hose body and a connecting portion formed coaxially and integrally with an end portion of the hose body and having an inserting inner peripheral surface, and a mating member made of structural material having a tubular inserting end portion for inserting into the connecting portion of the resin hose. The tubular inserting end portion includes a ring-shaped contacting surface and an inserting outer peripheral surface. In the hose body, at least the end portion is made of hard thermoplastic resin and is molded by a blow molding method. The connecting portion is made of soft thermoplastic resin and is molded by an injection molding method. The ring-shaped contacting surface of the tubular inserting end portion of the mating member is brought into contact with the end portion of the hose body, and the inserting outer peripheral surface of the tubular inserting end portion is fitted with the inserting inner peripheral surface of the connecting portion. Thereby, the resin hose and the mating member are connected together.

TECHNICAL FIELD

The present invention relates to a resin hose connecting structuresuitable for use as a connecting structure in which an air duct hose, afiller hose or the like is connected with a mating member.

BACKGROUND ART

For example, in the case of an air hose, a filler hose or the like, itis recently examined and actually practiced that a resin hose is usedinstead of a rubber hose. The resin hose has the following advantages.The resin hose is capable of decreasing weight of the hose in comparisonwith the rubber hose since the specific gravity of resin is small. Theresin hose is capable of forming an integral-mold article comprising asoft portion and a hard portion. The resin hose is capable of selectinga design for a hose-configuration and so on optionally.

In the case of the resin hose, a hard resin material is used as aportion requiring hardness, a soft resin material is used as a portionrequiring softness, and it can be accomplished that the hardhose-portion and the soft hose-portion are molded integrally by usingtwo kinds of resin-material.

On the other hand, in the case of the rubber hose, it is difficult toaccomplish that the hard hose-portion and the soft hose-portion aremolded integrally. In the case of the rubber hose, in general, a metalpipe is used as a portion requiring hardness, a rubber hose is used as aportion requiring flexibility, and thereby both are constructedtogether.

In the case of the resin hose, as understood from the above-described,the number of parts can be decreased and a production cost can bedecreased since the integral-mold hose is formed by molding the softportion and hard portion together.

In the case of the resin hose, to select the design for ahose-configuration and so on optionally, which means that the hose issufficiently endurable against deformation when a negative pressure isapplied on the hose. In the case of the rubber hose, for example,providing that the hose is in a flat-shape in cross-section, theflat-shape portion is likely to deform. Accordingly, the selection ofthe design for hose-configuration and so on is restricted in comparisonwith the resin hose.

By the way, in the case of the resin hose, a blow molding method ispreferably used to form the hose. In the blow molding method, a tubularor a bladder-like parison is swelled by blowing an air so that theparison is closely adhered to an inner surface of the mold-die. As aresult, the parison is formed in the predetermined shape. Thus, theouter surface of the mold-hose is accurately formed in the predeterminedshape by the mold-die, but the inner surface of the mold-hose is formedunder the free condition. Therefore, the inner surface of the mold-hoseshows bad characteristics in its shape and dimensional accuracy.

In the hose, a mating member is inserted into the inside of the hose-endportion constituting a connecting portion, and both are connectedtogether. In this arrangement, it is required that sealing capacity canbe ensured between the mating member and the connecting portion.Providing that the mold-hose shows bad characteristics in its shape anddimensional accuracy, namely, that defects such as an unevennessthickness, an unevenness dimension, a biased thickness, and a ruggednessare generated, the sealing capacity can't be ensured satisfactorilybetween the mating member and the connecting portion.

Then, in the case of the aforementioned resin hose formed by the blowmolding method, the inner surface is polished for finishing-treatment sothat the inner surface of the hose is formed in the predeterminedaccurate shape and dimension.

In the case where the above-mentioned polishing is performed, not onlyhose forming steps become complicated, but also polishing powders remainat and around the polishing portion. Therefore, a cleaning step forremoving the polishing powders is needed, and the hose forming stepsbecome more and more complicated. As a result, the production cost ofthe hose is increased.

In order to the aforementioned problems, as illustrated in FIG. 9, thepresent inventors have developed a process invention, in which a hosebody 100 is formed by blow-molding thermoplastic resin, and the hosebody 100 is disposed in a mold-die 102, next a tubular connectingportion 104 (an end portion of the hose in an axial direction) forconnecting a mating member is formed by injection-molding. Thisinvention has been filed as a patent application (Japanese PatentApplication No.3-39145).

In this process invention of the patent application; since the innerperipheral surface of the connecting portion 104 can be formed in thepredetermined shape and the predetermined dimension, the polishing ofthe inner peripheral of the connecting portion 104 isn't needed asdistinct from the conventional hose. In this process invention,therefore, not only the polishing step is omissible, but also thecleaning step for removing the polishing powders is unnecessary, therebythe whole number of steps of the process can be reduced and theproduction cost can be decreased.

Further, in this process invention of the patent application, the innerperipheral surface of the connecting portion 104 can be formed moreaccurately in comparison with that of the connecting portion polished.Accordingly, for instance, when the mating member such as a metal pipeis inserted into the connecting portion of the hose, the reliability ofthe sealing capacity between the mating member and the hose is improved.

Furthermore, this process invention of the patent application isadvantageous in achieving that the hose body can be made of hard resinand the connecting portion can be made of soft resin.

For example, in the case of the air duct hose for an automobile, sincethe negative pressure is applied to the hose during use of the hose,providing that the hose body is made of the soft material, thecross-section of the hose body is deformed, and the section thereof isreduced. Therefore, the pressure-loss of an air passing through the hoseis increased, the amount of the passing-air is decreased, and therebythe incomplete combustion of the engine may be caused. Providing thatthe whole hose is made of a hard material with the object of preventingthese problems, the sealing capacity between the hose and the matingmember is decreased during connecting.

When the hose is made of the hard material and the connecting portion ismade of the soft material in view of the above-mentioned processinvention of the patent application, not only the hose can possessmechanical strength such as negative-pressure resistance, but also thesealing capacity between the connecting portion and the mating membercan be improved. Of course, when a bellows portion is formed in the hosebody, or when the bellows is made of soft resin, the hose can becomemore flexible.

By the way, in the case where the mating member is inserted into thehose, as shown in FIG. 10(A), a concaved portion 106, whose innerdiameter is large, is formed at an end portion of the connecting portion104, and the mating member is inserted into the concaved portion 106 forfixation. In this arrangement, however, when oscillation or bendingforce is applied to the hose, as understood from FIG. 10(B), a largestrain or a large stress generates partially in the connecting portion104 made of the soft material.

Therefore, cracks generate or progress in the connecting portion 104,the hose may come to be broken off finally.

The present invention has been developed in view of the solving ofaforementioned problems.

DISCLOSURE OF INVENTION

A resin hose connecting structure according to the present inventioncomprises:

a resin hose including a hose body in which at least an end portion ismade of a hard thermoplastic resin and is molded by a blow moldingmethod, and a connecting portion formed coaxially and integrally withthe end portion of the hose body and made of a soft thermoplastic resin,the connecting portion having an inserting inner peripheral surface hasan inner diameter being equal to or larger than an inner diameter of theend portion of the hose body; and

a mating member made of a structural material harder than the softthermoplastic resin, having a tubular inserting end portion forinserting into the connecting portion of the resin hose, the tubularinserting portion including a ring-shaped contacting surface disposed ata head thereof and an inserting outer peripheral surface disposed a rearof the ring-shaped contacting surface, the inserting outer surface to beinserted into the inserting inner peripheral surface of the resin hose;

wherein the ring-shaped connecting surface of the tubular inserting endportion of the mating member is brought into contact with the endportion of the hose body, and the inserting outer peripheral surface ofthe tubular inserting end portion is fitted with the inserting innerperipheral surface of the connecting portion so that the resin hose andthe mating member are connected together.

Advantageous effects accomplished in the above-mentioned patentapplication (Japanese Patent Application No.3-39145), in which theconnecting portion is formed by the injection molding, are similarlyobtained in the present invention. Further, in the present invention,the following advantageous effects are obtained. Namely, in the presentinvention, since the mating member is inserted into the resin hosethrough the connecting portion so that the mating member is brought intocontact with the end portion of the hose body for fixation, even whenoscillation or bending force is applied to the hose during use of thehose, it can be prevented that a large strain or a large stressgenerates partially in the connecting portion.

Also, in the connecting structure according to the present invention,the mating member is brought into contact with the end portion of thehose body, namely, the connecting portion made of the soft resin isn'tsubstantially interposed between the end portion of the hose body andthe mating member. Therefore, when the bending force or the like isapplied to the hose, the phenomenon in which the soft portion betweenthe end portion of the hose body and the mating member is bent greatly,isn't generated. And the bending force is equally applied to the wholehose in the present invention.

Therefore, in the present invention, in the case where the high-flexibleportion such as the bellows portion is disposed at an intermediateportion of the hose body, the bending force is absorbed by thehigh-flexible portion, and thereby a large partial force isn't appliedto the connecting portion made of soft resin.

Accordingly, the crack-generation or the crack-progress caused by thepartial stress is suppressed, and the hose-life is improved.

In addition, the inner peripheral surface of the connecting portion madeof soft resin isn't directly exposed to fluid, such as gasoline flowingthrough the hose, blowby-gas flowing from the engine, or the like, andthereby life-deterioration caused by the fluid can be avoided.

In the case of the filler hose in which the connecting portion made ofsoft resin is directly exposed to the gasoline, the gasoline penetratesthrough the wall of the hose outwardly. Because gasoline-penetrationresistant of the soft resin is inferior to that of the hard resin. But,in the case where the connecting structure according to the presentinvention is applied to the filler hose, since the connecting portionmade of soft resin isn't directly exposed to the fluid, the penetratedamount of the gasoline can be decreased.

Oil-resistant and blowby-gas resistant of the soft resin are inferior tothat of the hard resin. Accordingly, in the case of the air duct hose,when the inner peripheral surface of the connecting portion made of softresin is directly exposed, the inner peripheral surface of theconnecting portion is easy to become deterioration. But, in theconnecting structure according to the present invention, since the innerperipheral surface of the connecting portion isn't directly exposed tooil or blowby-gas, the hose-deterioration caused by them can besuppressed.

Further, since the connecting portion isn't directly exposed to thefluid in the present invention, it is possible to select the soft resinin which oil-resistant, blowby-gas resistant or the like isn't excellentbut other properties are excellent. Therefore, it can be accomplished toselect a material of the connecting portion optionally.

Furthermore, in the connecting structure according to the presentinvention, when the case where the connecting portion formed coaxiallywith the hose body comprises the inserting inner peripheral surfacehaving an inner diameter being larger than that of the hose body, andwhen an inner diameter of the tubular inserting end portion of themating member is in accordance with an inner diameter of the hose body,the fluid can flow smoothly through the resin hose and the matingmember.

Since an amount of the soft resin material which is expensive can bedecreased, the connecting structure according to the present inventionis advantageous in reducing the production cost of hose.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(A) and 1(B) are drawings which show a hose connecting structureof a preferred embodiment according to the present invention.

FIGS. 2 is a perspective drawing which shows the whole structure of thehose described in FIG. 1.

FIGS. 3(A), 3(B), 3(C) and 3(D) are drawings of the modifications of thepresent invention.

FIGS. 4(A), 4(B), 4(C), 4(D), 4(E) and 4(F) are drawings of the furthermodifications of the present invention.

FIGS. 5(G), 5(H), 5(I) and 5(J) are drawings of the still furthermodifications of the present invention.

FIGS. 6(A), 6(B), 6(C), 6(D) and 6(E) are drawings of the still furthermodifications of the present invention.

FIGS. 7(A), 7(B), 7(C), 7(D), 7(E) and 7(F) are drawings of the stillfurther modifications of the present invention.

FIGS. 8(A), 8(B), 8(C), 8(D), 8(E), 8(F) and 8(G) are drawings of thestill further modifications of the present invention.

FIGS. 9(A), 9(B) and 9(C) are drawings of the still furthermodifications of the present invention.

FIGS. 10(A) and 10(B) are drawings to explain the problems to be solved.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, the embodiments according to the present invention will beexplained on the basis of the accompanying Figures.

As shown in FIG. 2, numeral 10 shows a resin hose employed as an airduct hose or the like. This resin hose comprises a hose body 12 and aconnecting portion 14. The hose body 12 is formed by blow-molding hardthermoplastic resin. The connecting portion 14 which is formedintegrally with the hose body 12 and which is formed byinjection-molding soft thermoplastic resin into a mold-die where thehose body 12 is disposed.

In the central area of the resin hose 10, a bellows portion ispositioned for giving flexible property to the hose body 12. The bellowsportion 15 may be made of soft resin for increasing the flexibility ofthe bellows portion 15.

In the hose 10, polypropylene resin having a Rockwell-hardness (R-scale)94 (for instance: EC-9B, produced by Mitsubishi Petrochemical Co. Ltd.)can be exemplified as hard resin for molding the hose body 12, and themixture of polypropylene resin and EPDM polymer-alloy having aShore-hardness A 75 (for instance: Sant-plane 101-75, produced by NipponMonsant Co. Ltd.) can be exemplified as hard resin for molding theconnecting portion 14.

FIGS. 1(A) and 1(B) show a cross-sectional structure in the surroundingsof the end portion of the hose 10. As shown in FIG. 1, in the hose 10 ofthe present embodiment, a large-diameter portion 16 is formed at an endportion of the hose body 12, and an expanded inner peripheral surface 18is formed on an inside of the large-diameter portion 16.

A tubular-shaped projecting portion 20 extending in an axial directionis formed on the connecting portion 14, and the projecting portion 20 ispiled so as to cover the expanded inner peripheral surface 18, andthereby the projecting portion 20 is integrated.

In the resin hose 10 of the present embodiment, an outer diameter of theconnecting portion 14 is equal to an outer diameter of thelarge-diameter portion 16 of the hose body 12, an inner diameter of theconnecting portion 14 is larger than an inner diameter of the hose body12, and thereby the whole inner peripheral surface of the connectingportion 14 corresponds to an inserting inner peripheral surface 22.

A metal pipe 24, which constitutes the mating member of the presentinvention, is inserted into a tubular-shaped receiver hole defined bythe inserting inner peripheral surface 22 through an opening of theconnecting portion 14. The top-end of metal pipe 24 is brought intocontact with an end surface of a stepped portion 32 of the hose body 12.Under these circumstances, a clamping member 19 is tightened at aclamping groove 17 positioned on the outer peripheral surface of theconnecting portion 14, and thereby the hose 10 and the mating metal pipe24 are fixed and connected. In the present embodiment, a ring-shapedtop-end surface of the metal pipe 24 corresponds to the ring-shapedcontacting surface of the present invention, and the outer peripheralsurface of the head of the metal pipe 24 corresponds to the insertingouter peripheral surface of the present invention.

Here, the clamping member 19 includes a band 21 and a tightening member23, the tightening member 23 is fastened by use of a bolt and so on, theband 21 is contracted in a radial direction, and thereby the connectingportion 14 is fastened inwardly. The clamping member 19 shown in FIG.1(B) is a mere example of the present invention, other various clampingmembers being modified can be employed.

The inner diameter of the above-mentioned hose body 12 is equal to thatof the mating metal pipe 24; so the inner peripheral surface of the hosebody 12 is on a level with that of the metal pipe 24. Accordingly, afluid can flow smoothly through the hose body 12 and the metal pipe 24.

In the case of the resin hose 10 according to the present embodiment,the top-end of the hard metal pipe 24 is directly brought into contactwith the end surface of the stepped portion 32 of the hose body 12.Therefore, when compressive force is applied to the area between theresin body and metal pipe 24, the resin hose 10 can endure the relativelarge compressive force. Also, since the large-diameter portion 16 isformed with the hose body 12, the resin hose 10 can endure relativelarge oscillation or bending force applied to the hose 10.

Further, the bellows portion 15 positioned at the central area of thehose body 12 can absorbed oscillation or bending force; so alarge-strain or a partial stress-concentration isn't generated in theconnecting portion 14 made of soft resin. Therefore, the life of thehose 10 is improved.

Also, since the inner peripheral surface of the connecting portion 14isn't directly exposed to the fluid flowing through the hose, such asblow-by gas, gasoline, oil and so on, the hose-deterioration caused bythe chemical operation of the fluid is prevented, thereby improving thelife of the hose.

Besides, it isn't required that the portion constituting thelarge-diameter portion 16 is made of soft resin whose cost is expensive;therefore, the consumed amount of the expensive soft resin can bereduced, and the production cost of hose can be reduced too.

As for the connecting structure comprising the hose 10 and the metalpipe 24, various structures can be employed in addition to theabove-described embodiment.

FIGS. 3(A) to 3(D) show other preferred embodiments. In an embodimentshown in FIG. 3(A), a connecting portion 14 is formed in astraight-shape by an injection molding method so as to cover the outerperipheral surface of the end portion of the hose body 12, and an innerdiameter of the connecting portion 14 is equal to an outer diameter ofthe hose body The inner peripheral surface of the connecting portion 14which projects from the hose body 42 in an axial direction and whichconstitutes the inserting inner peripheral surface 22. The metal pipe 24is inserted into the inserting inner peripheral surface 22, and therebythe top-end surface of the metal pipe 24 is brought into contact withthe end surface of the hose body 12.

In an embodiment shown in FIG. 3(B), a connecting portion 14 is formedby an injection molding method so as to cover an outer surface beingalong a centrifugal direction of a hose body 12. A stepped portion 26 ispositioned on the connecting portion 14, the stepped portion 26 covers asurface being along the centrifugal direction of the hose body 12, andthereby both is welded or fused to be formed integrally. An innerperipheral surface of the portion projecting from the hose body 12 in anaxial direction constitutes an inserting inner peripheral surface 22whose inner diameter is smaller than an outer diameter of the hose body12. The outer peripheral surface of the metal pipe 24 is in contact withthe inserting inner peripheral surface 22.

In an embodiment shown in FIG. 3(C), an edge portion 28 is cut off at anouter peripheral surface of an end portion of a hose body 12. After thehose body 12 having the edge portion 28 is set in the mold-die, aconnecting portion 14 is formed by an injection molding method. Aninserting inner peripheral surface 22 is positioned at an inside of theportion projecting from the hose body 12, and an inner diameter of theinserting inner peripheral surface 22 is equal to an outer diameter ofthe cut-off portion. A metal pipe 24 is inserted into the insertinginner peripheral surface 22.

In an embodiment shown in FIG. 3(D), an outer peripheral surface of anend portion of a hose body 12 is cut off in a range extending at somelength. After the hose body 12 having the cut-off portion is set in amold-die, a connecting portion 14 is formed by an injection moldingmethod. In this embodiment, an outer diameter of the connecting portion14 is equal to an outer diameter of the hose body 12. In addition, aninserting inner peripheral surface 22 is positioned at the inside of theportion projecting from the hose body 12, the metal pipe 24 is insertedinto the inserting inner peripheral surface 22 for fixation.

FIG. 4 and FIG. 5 show another preferred embodiments of the presentinvention.

The structure shown in FIG. 4(B) comprises a resin hose 10 shown in FIG.4(A) and a metal pipe 24. An end portion of a hose body 12 constitutingthe resin hose 10 has a expanded portion including a stepped portion 33whose inner diameter is continuously larger as it approaches an openingthereof. A connecting portion 14 is welded with a surface being along acentrifugal direction in the stepped portion 33 of the hose body 12, aninner peripheral surface and an axial end surface of the expandedportion of the resin hose.

Also, the connecting portion 14 includes an inserting inner peripheralsurface 22 has an inner diameter being larger than an inner diameter ofthe hose body 12.

A ring-shaped projection portion 30 which is positioned at a top-end ofthe metal pipe 24 and which is encircled in a circumferential direction.In the present embodiment, an inclined surface disposed at a top-side ofthe projection portion 30 constitutes the ring-shaped contactingsurface. By inserting the metal pipe 24 into the connecting portion 14,the outer peripheral surface of the leading end of the metal pipe 24 isfitted to the inserting inner peripheral surface 22, the projectionportion 30 is brought into contact with the stepped portion 33 of thehose body 12 as shown in FIG. 4(B). In these circumstances, the clampingmember 19 is tightened for fixing the metal pipe 24.

An outer diameter of the most projecting portion of the projectionportion 30 is larger than the inner diameter of the inserting peripheralsurface 22. Therefore, in the connecting structure shown in FIG. 4(B),the area of the inserting peripheral surface 22 being in contact withthe projection portion 30 is elastically deformed, and thereby the innerdiameter of the inserting peripheral surface 22 is partially enlarged inthe radial direction. The projection portion 30 of the metal pipe 24includes the expanded portion projecting in the centrifugal direction,the expanded portion of the projection portion 30 is partially engagedwith the inside of the connecting portion 14, and thereby the hose 10 isconnected with the metal pipe 24. Further, when the projection portion30 of the metal pipe 24 is inserted into the inserting peripheralsurface 22 of the connecting portion 14, the projection portion 30enters the connecting portion 14 forcibly with a temporary expansion ofthe inserting peripheral surface 22.

In this embodiment, even when the hose 10 inclines to the metal pipe 24,the connecting structure of this embodiment is advantageous inmaintaining the contacted condition in which the metal pipe 24 isbrought into contact with the hose body 12.

In an embodiment shown in FIG. 4(C), a resin hose 12 having the samestructure as the resin hose 12 shown in FIG. 4(A) is employed, and ametal pipe 24 differing slightly from the metal pipe 24 shown in FIG.4(A) is employed. The metal pipe 24 shown in FIG. 4(C) has atubular-shaped small-diameter portion 34 extending from a projectionportion 30 in an axial direction. An outer peripheral surface of thesmall-diameter portion 34 is fitted to the inner peripheral surface ofthe hose body 12. The arrow in the drawing illustrates a clamping placewhere the hose is clamped by use of the clamping member (it is similarlyin the following embodiments).

Further, in an embodiment shown in FIG. 4(D), a tapered portion 36 whichcorresponds to the ring-shaped contacting surface of the presentinvention and which is positioned at a head of a metal pipe 24 insteadof the projection portion 30 shown in FIG. 4(C). A small-diameterportion 34 is extended from the tapered portion 36 in an axialdirection. The tapered portion 36 is brought into contact with thestepped portion 33 of the hose body 12, and the small-diameter portion34 is inserted into the inner peripheral surface of the hose body 12.

In embodiments shown in FIG. 4(E) and FIG. 4(F), other metal pipes 24are employed. The metal pipe 24 has a slightly-narrowed head and aprojection portion 37 disposed at a distance from the top-end of themetal pipe 24. An outer diameter of one side by way of the projectionportion 37 is equal to that of the other side by way of the projectionportion 37. The projection portion 37 differs from the projectionportion 30 shown in FIG. 4(B) in the function: the projection portion 37enters the inserting peripheral surface 22 of the connecting portion 14forcibly, and thereby the projection portion 37 increases the sealingcapacity of the contact area and operates as a resistant-portion forpreventing the hose 10 coming off. The ring-shaped contacting surface ofthe present invention corresponds to an inclined surface which isslightly narrowed in a ring-shape at the top-end of the metal pipe 24 inthe present embodiment.

The projection portion 37 shown in FIG. 4(E) acts a similar functionexcept for a distance from the top-end of the pipe 14. The both sidesfacing by way of the projection portion 37 constitute the insertingouter peripheral surface of the present invention.

FIG. 5(G) and FIG. 5(H) show embodiments where an end portion of a hosebody 12 is expanded in a trumpet-shape, a projection portion 30 of themetal pipe 24 is inserted into an inserting peripheral surface 22 and isbrought into contact with the expanded end portion 38.

FIG. 5(I) shows an embodiment where a projection portion 30 of a metalpipe 24 is brought into contact with the expanded end portion 38 and thesmall-diameter portion 34 is inserted into the inside of the hose body12.

FIG. 5(J) shows an embodiment where a tapered portion 36 of a metal pipe24 is brought into contact with the expanded end portion 38, and asmall-diameter portion 34 of the head of the metal pipe 24 is insertedinto the inside of the hose body 12.

FIGS. 6(A) to 6(E) show other various embodiments of the presentinvention. In these embodiments, a resin hose 10 shown in FIG. 6(A) isemployed. An end portion of a hose body 12 constituting the resin hose10 includes an expanded portion comprising a stepped portion 33 whoseinner diameter is increasing as it approaches an opening. A connectingportion 14 is formed in order that the connecting portion 14 is weldedwith a surface of the stepped portion 33 of the hose body 12, the innerperipheral surface and the axial-end surface of the expanded portion. Aninner diameter of an inserting peripheral surface 22 of the connectingportion 14 is equal to that of the hose body 12 shown in FIG. 6(A).

In an embodiment shown in FIG. 6(B), a ring-shaped projection portion 30is formed at the top-end of a metal pipe 24 whose outer diameter isequal to an inner diameter of an inserting peripheral surface 22. Anouter diameter of the summit of the projection portion 30 is larger thanthe inner diameter of the inserting peripheral surface 22. Therefore,when the metal pipe 24 is inserted into a connecting portion 14, theprojection portion 30 enters the connecting portion 14 forcibly in anaxial direction with a temporary expansion of the inserting peripheralsurface 22, and the metal pipe 24 is stopped since it is brought intocontact with the stepped portion 33 of the hose body 10.

FIG. 6(C) shows an embodiment where a small-diameter portion 34 ispositioned at the head of the metal pipe 24. An outer diameter of thesmall-diameter portion 34 is substantially equal to the inner diameterof the hose body 12, and the small-diameter portion 34 is inserted intothe inside of the hose body 12.

FIG. 6(D) shows an embodiment where a rib-like portion 40 having asemi-circle shape in cross-section is positioned at a top-end of themetal pipe 24. The rib-like portion 40 acts the similar function to thering-shaped projection portion 30.

FIG. 6(E) shows a still another metal pipe 24, in which a plurality ofring-shaped protruding portions 42 are disposed at a predeterminedintervals in an axial direction, so that the protruding portions 42 areformed in a sawing-shape and encircled in the circumferential direction.An inclined surface of the protruding portion 42 disposed at a top-endof the metal pipe 24 corresponds to the ring-shaped contacting surfaceof the present invention.

In each of the structures shown in FIG. 6(B), FIG. 6(C) and FIG. 6(D),the outwardly-expanded portion of the projection portion 30, therib-like portion 40 and the protruding portion 42 are engaged with theinserting peripheral surface 22 of the connecting portion 14 made of thesoft resin.

By the engagement of the inserting peripheral surface 22 and the matingmember 24, it is effectively prevented that internal fluid enters aboundary between the connecting portion 14 and the metal pipe 24.

Further, under the condition that the clamping member is tightened, theprojection portion 30, the rib-like portion 40 and the protrudingportion 42 respectively work so as to prevent the metal pipe 24 and thehose 10 from disconnecting. An embodiment shown in FIGS. 7(A) to 7(F)features a resin hose 10. An end portion of a hose body 12 of a resinhose 10 comprises a large-diameter portion 16 having a stepped portion33 whose inner diameter is continuously larger as it approaches anopening thereof, a connecting portion 14 is welded with the end surfaceand the outer peripheral surface of the large-diameter portion 16, andan inner diameter of the inserting peripheral surface 22 is equal tothat of the large-diameter portion 16.

A metal pipe 24 shown in FIG. 7(B) and FIG. 7(C) has an outer diameterbeing the same size as an inner diameter of the inserting peripheralsurface 22, a ring-shaped projection portion 30 is formed by bulging thehead of the metal pipe 24. In the metal pipe 24 in shown FIG. 7(B), atubular-shaped portion extending from the projection portion 30 isformed shortly in an axial direction, a ring-shaped inclined surfacedisposed at the projection portion 30 is brought into contact with theend surface of a large-diameter portion 16 of a hose body 12 in theengaged condition. Therefore, the ring-shaped inclined surface of thisprojection portion 30 corresponds to the ring-shaped contacting surfaceof the present invention.

In a metal pipe 24 shown in FIG. 7(C), a tubular-shaped portion whichextends from a projection portion 30 and which is lengthened in an axialdirection, the ring-shaped inclined surface disposed at the top-end of ametal pipe 24 is brought into contact with the stepped portion 33 of ahose body 12. Therefore, the ring-shaped inclined surface disposed atthe top-end of the metal pipe 24 corresponds to the ring-shapedcontacting surface of the present invention. The projection portion 30has the same function as the projection portion 37 shown in FIG. 4(E).

When a length of the large-diameter portion 16 of the resin hose 10shown in FIG. 7 is equal to a length of the tubular-shaped portion ofthe metal pipe 24, the ring-shaped inclined surface disposed on theprojection portion 30 is capable of coming into contact with the endsurface of the large-diameter portion 16 of the hose body 12, and thering-shaped inclined surface disposed at the top-end of the metal pipe24 is capable of coming into contact with the stepped portion 33 of thehose body 12. In this arrangement, the metal pipe 24 is brought intocontact with the resin body 12 in two places which are positioned atpredetermined intervals in an axial direction. The ring-shaped inclinedsurface of the projection portion 30 as well as the ring-shaped inclinedsurface of the top-end of the tubular portion of the metal pipe 24corresponds to the ring-shaped contacting surface of the presentinvention.

FIG. 7(E) and FIG. 7(F) show embodiments, where the resin hose 10illustrated in FIG. 7(D) is employed instead of the resin hoseillustrated in FIG. 7(A). The hose body 12 of the resin hose 10comprises a middle-diameter portion 44 having a first stepped portion46, and the large-diameter portion 16 having a stepped portion 33extending from the end of the middle-diameter portion 44. The connectingportion 14 is welded with the end surface and the outer peripheralsurface of the large-diameter portion 16, and an inner diameter of theinserting peripheral surface 22 is equal to that of the large-diameterportion 16. In these embodiments, a projection portion 30 of the metalpipe 24 is brought into contact with the stepped portion 33 of thelarge-diameter portion 16, or the top-end of the metal pipe 24 isbrought into contact with the stepped portion 46 of the middle-diameterportion 44.

FIGS. 8(A) to (G) show the other embodiments. In these embodiments shownin FIG. 8(B), FIG. 8(C) and FIG. 8(D), as shown in FIG. 8(A), aring-shaped convexed portion 48 is formed by expanding an innerperipheral surface of the hose body 12 slightly in a radial direction. Aprojection portion 30 or a rib-like portion 40 is elastically engagedwith the convexed portion 48, and clamping is accomplished by clampingmember 19 in the vicinity of the engaged area of the convexed portion48.

Further, in an embodiment shown in FIGS. 8 (G) and 8 (F), a convexedportion 48 and a stepped portion 33 is formed in the hose body 12, theconvexed portion 48 is elastically engaged with the projection portion30 etc, and the top-end of the metal pipe 24 is brought into contactwith the stepped portion 33.

Although the present invention has been detailed on the basis of thepreferred embodiments thereof, they are mere examples. The followingstructural modifications is applicable in the present invention: notonly the connecting portion positioned at the end portion in the axialdirection is connected to the mating member, but also a connectingportion positioned at a midway portion of the hose is connected to amating member. It will be apparent to one of ordinary skill in the artthat many changes can be made without departing from the split or thescope of the present invention.

I claim:
 1. A resin hose connecting structure comprising:a resin hoseincluding a hose body and a soft thermoplastic resin, injection moldedconnecting portion extending coaxially and integrally with a hardthermoplastic resin, blow molded end portion of said hose body, saidconnecting portion having an axially extending inner peripheral surface;and a mating member made of structural material having a tubularinserting end portion for inserting into said connecting portion of saidresin hose, said tubular inserting end portion including a ring-shapedcontacting surface disposed at a head thereof and an inserting outerperipheral surface disposed axially spaced from said ring-shapedcontacting surface, said ring-shaped contacting surface to be contactedto the inner surface of said hose body and said inserting outerperipheral surface to be inserted into said inserting inner peripheralsurface of said connecting portion of said resin hose; said head of saidtubular inserting end portion of said mating member being inserted atleast to an abutting edge of said end portion of said hose body, andsaid inserting outer peripheral surface of said tubular inserting endportion is fitted with said inserting inner peripheral surface of saidconnecting portion with said connecting portion extending radially fromsaid tubular inserting end portion and forming an exterior surface ofsaid resin hose which receives of a clamping member entirely on saidexterior surface of said resin hose on said connecting portion so thatsaid resin hose is bendable at said connecting portion with respect tosaid end portion.
 2. A resin hose connecting structure according toclaim 1,wherein said end portion of said hose body for coming intocontact with said ring-shaped contacting surface is an end surface ofsaid end portion of said hose body.
 3. A resin hose connecting structureaccording to claim 1,wherein said end portion of said hose body forcoming into contact with said ring-shaped contacting surface is atapered surface which is disposed at a side of an end surface of saidhose body and which has sn increasing inner diameter as it approaches anopening thereof.
 4. A resin hose connecting structure according to claim1,wherein said end portion of said hose body for coming into contactwith said ring-shaped contacting surface is a convexed portion which ismade by expanding an inner peripheral surface annularly and slightly ina radial direction.
 5. A resin hose connecting structure according toclaim 1,wherein said end portion of said hose body includes a steppedportion and a large-diameter portion connected with said hose body byway of said stepped portion, and said end portion of said hose body forcoming into contact with said ring-shaped contacting surface is at leastone of an end surface of said stepped portion and an end surface of saidlarge-diameter portion.
 6. A resin hose connecting structure accordingto claim 1,wherein said end portion of said hose body includes a firststepped portion, a middle-diameter portion connected with said hose bodyby way of said first stepped portion, a second stepped portion, and alarge-diameter portion connected with said middle-diameter portion byway of said second stepped portion, and said end portion of said hosebody for coming into contact with said ring-shaped contacting surface isat least one of an end surface of said first stepped portion and an endsurface of said second stepped portion.
 7. A resin hose connectingstructure according to claim 1,wherein said connecting portion is weldedwith at least an end surface of said hose body, and said inserting innerperipheral surface of said connecting portion is formed coaxially withan inner peripheral surface of said hose body.
 8. A resin hoseconnecting structure according to claim 1,wherein said end portion ofsaid hose body includes a stepped portion and a large-diameter portionconnected with said hose body by way of said stepped portion, saidconnecting portion of said hose body is welded with at least one of aninner peripheral surface of said large-diameter portion and an endsurface of said large-diameter portion, and an inner diameter of saidinserting inner peripheral surface of said connecting portion is smallerthan an inner diameter of said large-diameter portion.
 9. A resin hoseconnecting structure according to claim 1,wherein said ring-shapedcontacting surface of said mating member is an inclined surface which isformed at an end surface of said tubular inserting end portion.
 10. Aresin hose connecting structure according to claim 1, wherein saidtubular inserting end portion includes a ring-shaped projection portionand said ring-shaped contacting surface of said mating member is aninclined surface which is formed at said projection portion.
 11. A resinhose connecting structure according to claim 1,wherein said tubularinserting end portion of said mating member includes s tubular portionand a small-diameter portion disposed at a head of said tubular portion,said tubular portion having said inserting outer peripheral surface,said small-diameter portion whose outer diameter is smaller than anouter diameter of said tubular portion, and said ring-shaped contactingsurface of said mating member is a ring-shaped tapered portion whichconnects said tubular portion with said small-diameter portion.
 12. Aresin hose connecting structure according to claim 1, wherein saidtubular inserting end portion of said mating member includes asmall-diameter portion which is disposed at an edge portion of saidring-shaped contacting portion and which is inserted into an innerperipheral surface of said hose body.
 13. A resin hose connectingstructure according to claim 1,wherein said tubular inserting endportion of said mating member includes a projection portion whichprojects annularly and which is engaged with said inserting innerperipheral surface of said connecting portion by enlarging saidinserting inner peripheral surface in a radial direction.
 14. A resinhose connecting structure comprising:a resin hose including a hose bodyin which at least an end portion is made of hard thermoplastic resin andis molded by a blow molding method, and a connecting portion formedcoaxially and integrally with said end portion of said hose body andmade of soft thermoplastic resin, said connecting portion having aninserting inner peripheral surface with an inner diameter equal to orlarger than an inner diameter of said end portion of said hose body; anda mating member made of structural material harder than said softthermoplastic resin, having a tubular inserting end portion forinserting into said connecting portion of said resin hose, said tubularinserting portion including a ring-shaped contacting surface disposed ata head thereof and an inserting outer peripheral surface disposedaxially spaced from said ring-shaped contacting surface, said insertingouter surface to be inserted into said inserting inner peripheralsurface of said resin hose; said ring-shaped connecting surface of saidtubular inserting end portion of said mating member is brought intocontact with said end portion of said hose body, and said insertingouter peripheral surface of said tubular inserting end portion is fittedwith said inserting inner peripheral surface of said connecting portionso that said resin hose and said mating member are connected together,said tubular inserting end portion of said mating member includes atubular portion and a small-diameter portion disposed at a head of saidtubular portion, said tubular portion having said inserting outerperipheral surface, said small-diameter portion whose outer diameter issmaller than an outer diameter of said tubular portion, and saidring-shaped contacting surface of said mating member is a ring-shapedtapered portion which connects said tubular portion with saidsmall-diameter portion.